The objective of the clinical research effort of National Bladder Cancer Collaborative Group A is to improve the care of patients with bladder carcinoma through studies of different aspects of clinical management according to carefully designed protocols. These are conducted at several Collaborating Institutions (CI) by multidisciplinary teams of physicians, including urologists, radiation therapists, medical oncologists and pathologists. A Central Statistical Office is responsible for collection organization and analyses of data, and an Administrative Center is responsible for program coordination and control. A Central Pathology Laboratory is responsible for the uniform evaluation, classification and analysis of pathologic and cytologic material. The Central Pathology Laboratory (CPL) proposes to: 1) Confirm the diagnosis of bladder cancer at the time of patient entry into the NBCCGA Surveillance Protocol (Ia) and to confirm the presence of those specific histopathologic features which will determine the eligibility of patients for specific therapy protocols; 2) to provide detailed histopathologic and cytologic information to the Statistical Center on review of accessioned material; 3) to review appropriate histologic material with CI pathologists looking particularly at cases with diagnostic differences between CPL and CI pathologists in order to expand our use of pathologic prognostic indicators; 4) to work with GI cytopathologists toward the acceptance and utilization of a standard method for evaluating and processing cytologic preparations; 5) to test the usefulness of cell surface markers as predictors of the aggressive potential of bladder carcinomas; 6) to provide resources, support and leadership within NBCCGA for the evaluation and interpretation of cytologic and histopathologic data.